what is priming in pump

Priming in a pump means filling the pump casing and suction line completely with liquid before starting the pump so that all air, gas, or vapour is removed and the pump can create proper suction and flow.

Quick Scoop

• Priming is done by filling the pump and suction pipe with the liquid to be pumped (often water), pushing out trapped air.

• It is especially important for centrifugal pumps, which cannot pump air and will just spin (air binding) if not primed.

• Without proper priming, the pump may have no flow, suffer cavitation, overheat, and damage seals, impeller, and bearings.

• Some pumps are designed as self‑priming, meaning they can automatically remove air from the suction line once there is some liquid in the casing.

Why priming is required

• To remove air/gas from casing and suction line so liquid directly contacts the impeller and a vacuum (suction) can be created.

• To prevent cavitation (vapour bubbles forming and collapsing), which causes noise, vibration, and mechanical damage.

• To avoid dry running and overheating, since liquid also cools and lubricates internal parts.

• To ensure rated head (pressure) and flow are achieved in operation.

Simple example

If you start a garden centrifugal pump connected to a tank but the suction pipe is full of air, the impeller will just churn air and no water will rise; once you pour water into the casing and suction line (priming), the pump can form suction and begin lifting water smoothly.

Information gathered from public forums or data available on the internet and portrayed here.